Photosynthesis on Earth can occur in a diversity of organisms in the photosynthetically active radiation (PAR) range of 10 nmol of photons m(-2) s(-1) to 8 mmol of photons m(-2) s(-1). Similar considerations would probably apply to photosynthetic organisms on Earth-like planets (ELPs) in the continuously habitable zone of other stars. On Earth, starlight PAR is inadequate for photosynthetically supported growth. An increase in starlight even to reach the minimum theoretical levels to allow for photosynthesis would require a universe that was approximately ten million times older, or with a ten million times greater density of stars, than is the case for the present universe. Photosynthesis on an ELP using PAR reflected from a natural satellite with the same size as our Moon, but at the Roche limit, could support a low rate of photosynthesis at full Moon. Photosynthesis on an ELP-like satellite of a Jupiter-sized planet using light reflected from the planet could be almost 1% of the rate in full sunlight on Earth when the planet was full. These potential contributions to photosynthesis require that the contribution is compared with the rate of photosynthesis driven by direct radiation from the star. Light pollution on Earth only energizes photosynthesis by organisms that are very close to the light source. However, effects of light pollution on photosynthesis can be more widespread if the photosynthetic canopy is retained for more of the year, caused by effects on photoperiodism, with implications for the influence of civilizations on photosynthesis.

Bats may be vulnerable to predation during evening emergence and morning return to their roosts. Early emergence increases the risk of exposure to raptorial birds, but emerging late confers a risk of missing the dusk peak of aerial insects. Here, both emergence and return activity was studied in detail at the same roosts for the first time. We investigated six maternity colonies of pipistrelle bats (Pipistrellus pipistrellus and P. pygmaeus) in NE Scotland and recorded light levels and time of emergence and return of the bats with respect to sunset and sunrise on the same nights. Parameters of return activity generally occurred at lower light intensities than those of emergence. Therefore, the interval between dawn return and sunrise was generally longer than that between sunset and dusk emergence. Emergence and return were equal in duration. Bats clustered more on emergence in comparison with return during pregnancy and lactation, whereas during postlactation this trend was reversed.

The Army increasingly relies on night operations to accomplish its objectives. These night operations frequently require using Night Vision Goggles and other light-sensitive devices which are strongly affected by ambient lighting, a large component of which is urban. An urban illumination model is proposed for use in tactical decision aids and wargames which would allow for more accurate prediction of target acquisition ranges and increased realism in simulations. This model will build on previous research that predicts broadband brightness as a function of population and distance from the city center. Since city population and aerosols affect light distributions, the model is being extended and generalized for multiple city types and natural and man-made aerosols. An overview of the model along with future improvements will be presented.

The last few years have seen a huge increase in the transfer of coloured architectural lighting, derived from entertainment and theatre, into the urban and exterior environment. Part of the reason for this is that in the last 15 yr or so, there have been a number of important introductions in coloured lighting technology. These have transformed lighting practice, and while their widespread introduction is seen by some as an enrichment of the urban fabric, others see it as presenting considerable dangers, in terms of aesthetics, perception and in terms of civic identity. Its negative effects on the urban environment have been termed ‘colour blight’.

In this paper, the range of coloured lighting technologies is surveyed and other causes for the increase in coloured lighting are also discussed, together with the problems and benefits involved. Finally, some tentative means are put forward for resolving the problems caused by ‘colour blight’. Current good practice is illustrated by the author's own experience, including his consultancy's participation in a number of urban lighting strategies in the UK and elsewhere. This work involves implementation of a comprehensive lighting plan for the historic city of York, as part of the Urban Lighting Group consortium of three lighting design practices.